Fix cudaErrorLaunchOutOfResources: Kernel Resource Exceeded

Overview

cudaErrorLaunchOutOfResources occurs when a kernel requires more resources (registers, shared memory) than available per SM.

Error Messages

CUDA error: launch out of resources
cudaErrorLaunchOutOfResources

Common Causes

• •Too many registers per thread
• •Shared memory exceeds SM limit
• •Block size incompatible with resources
• •Dynamic shared memory too large

Solutions

// Instead of 1024 threads
kernel<<<grid, 256>>>();  // Try smaller block

nvcc --maxrregcount=32 kernel.cu

int maxBlocks;
cudaOccupancyMaxActiveBlocksPerMultiprocessor(
    &maxBlocks, kernel, blockSize, sharedMem);

Prevention Tips

• ✓Profile with nvcc --ptxas-options=-v
• ✓Use occupancy calculator
• ✓Consider register spilling tradeoff

Code Examples

Before (Problematic)

Exceeds max threads per block.

kernel<<<1, 2048>>>();  // Block too large

After (Fixed)

Within resource limits.

kernel<<<8, 256>>>();  // Equivalent work, smaller blocks

Frequently Asked Questions

Related Errors

Need help debugging CUDA errors? Download RightNow AI for intelligent error analysis and optimization suggestions.